3.1. Amiga

The support for Amiga formats is mainly aimed at users of emulators. The .ADF disk image format used with most emulators is a plain dump of the disk, without special headers or compression. As such, disktype doesn't need special support to work with it. All Amiga formats originated on the 68K platform and thus use big-endian byte order.

Broad information on Amiga file and disk formats can be found at http://perso.club-internet.fr/lclevy/amiga/formats.html. The .ADF format FAQ is of particular interest, it is located at http://perso.club-internet.fr/lclevy/adflib/adf_info.html.

3.1.1. The Amiga File System

The Amiga file system comes in several variants, but is used the same on floppies and on hard disk partitions. All variants store a boot block at the very beginning of the disk and a root block in the middle. Apparently the boot block does not contain any actual pointers to the root block, so its position must be determined (well, more like guessed) from disk parameters like block size, block count, and cylinder boundaries.

disktype only uses the boot block to recognize the format. It contains a signature and a flags field that determine the file system variant. There's the original file system (reported as "Amiga OFS file system"), and the later "fast" file system (reported as "Amiga FFS file system"). The "fast" file system has variants for better dealing with international characters (well, European accented characters as in ISO Latin 1, that is), and a variant using a "directory cache".

As mentioned, disktype is unable to locate the root block right now, and thus can't print any more information like volume name or size. It does, however, check the size of the file against standard floppy sizes and reports matches.

3.1.2. The Professional File System

All that is known about the "Professional File System" is its signature in the boot block. disktype reports it if found.

3.1.3. The Rigid Disk Partitioning Scheme

The so-called "Rigid Disk" partitioning scheme is used on hard disks and sometimes(?) on removable media like Zip disks. The Rigid Disk block can be located anywhere within the first 16 sectors of the disk. The structure itself is only 256 bytes in size and contains a pointer to a linked list of partition descriptors. Each of these is also 256 bytes in size, is located in a sector of its own somewhere on the disk, and contains a pointer to the next such descriptor.

It is somewhat unclear how exactly sector sizes other than 512 bytes are to be handled. In lack of further data (or actually any test images at all), disktype assumes 512 byte sectors and warns if the Rigid Disk block says different. disktype prints the "drive name" of each partition. The partition descriptor also contains information about the file system contained in the partition, which is decoded and printed. The contents of the partition will be analyzed in any case.